Photoacoustic sensor valve

Abstract

A system for measuring gas concentration includes a package having a cavity and a port, a photoacoustic gas sensor device within the package, and a Micro Electro Mechanical System (“MEMS”) valve separate from the photoacoustic gas sensor device placed over the port of the package and to allow ambient gas diffusion into the cavity in a first mode of operation, and to prevent ambient gas diffusion into the cavity and to acoustically isolate the cavity in a second mode of operation.

What is claimed is: 
     
       1. A Micro Electro Mechanical System (“MEMS”) valve comprising a first perforated backplate and a perforated membrane, wherein perforations in the first perforated backplate and perforations in the perforated membrane are non-overlapping in a plan view, and wherein the perforated membrane and the first perforated backplate are in an open configuration in a first mode of operation and in a closed configuration in a second mode of operation; and a second perforated backplate, and wherein the perforated membrane is between the first perforated backplate and the second perforated backplate. 
     
     
       2. The MEMS valve of  claim 1 , wherein a gap length between the first perforated backplate and the perforated membrane is different from a gap length between the second perforated backplate and the perforated membrane. 
     
     
       3. The MEMS valve of  claim 1 , wherein the first perforated backplate comprises a perforated insulated silicon layer, and wherein the perforated membrane comprises a perforated silicon layer. 
     
     
       4. The MEMS valve of  claim 1 , further comprising a cantilevered silicon substrate under the first perforated backplate and the perforated membrane. 
     
     
       5. The MEMS valve of  claim 1 , wherein the perforations in the first perforated backplate are arranged in a hexagonal or circular radial concentric pattern, and the perforations in the perforated membrane are arranged in a non-overlapping hexagonal or circular radial concentric pattern. 
     
     
       6. A PhotoAcoustic Sensor (“PAS”) valve comprising:
 a first membrane comprising an inner concentric pattern of perforations and an outer circular ring without perforations; and 
 a second membrane comprising a circular inner portion without perforations, a first outer circular ring having a concentric pattern of perforations, and a second outer circular ring without perforations, 
 wherein the inner concentric pattern of perforations of the first membrane and the concentric pattern of perforations of the second membrane are nonoverlaping in a plan view. 
 
     
     
       7. The PAS valve of  claim 6 , wherein the first membrane comprises a rigid backplate and the second membrane comprises a flexible membrane. 
     
     
       8. The PAS valve of  claim 6 , wherein the first membrane comprises a flexible membrane and the second membrane comprises a rigid backplate. 
     
     
       9. The PAS valve of  claim 6 , wherein the inner concentric pattern of perforations of the first membrane comprises a circular radial concentric pattern of perforations. 
     
     
       10. The PAS valve of  claim 6 , wherein the inner concentric pattern of perforations of the first membrane comprises a hexagonal radial concentric pattern of perforations. 
     
     
       11. The PAS valve of  claim 6 , wherein the first membrane comprises a circular bumpring. 
     
     
       12. The PAS valve of  claim 11 , wherein the circular bumpring is not in contact with the second membrane in a first mode of operation of the PAS valve. 
     
     
       13. The PAS valve of  claim 12 , wherein the circular bumpring is in contact with the second membrane in a second mode of operation of the PAS valve. 
     
     
       14. A monolithic acoustic valve comprising:
 a perforated insulated silicon backplate coupled to a substrate; and 
 a perforated silicon membrane coupled to the substrate, 
 wherein perforations in the perforated insulated silicon backplate and non-overlapping perforations in the perforated silicon membrane comprise a radial pattern emanating from a center portion of the monolithic acoustic valve to a peripheral portion of the monolithic acoustic valve in a plan view, and wherein the radial pattern comprises an inner pattern and a non-overlapping outer ringed pattern. 
 
     
     
       15. The monolithic acoustic valve of  claim 14 , further comprising an additional perforated insulated silicon backplate coupled to the substrate and adjacent to the perforated silicon membrane. 
     
     
       16. The monolithic acoustic valve of  claim 14 , wherein the inner pattern comprises a circular or hexagonal pattern on the perforated insulated silicon backplate. 
     
     
       17. The monolithic acoustic valve of  claim 14 , wherein the inner pattern comprises a circular or hexagonal pattern on the perforated silicon membrane. 
     
     
       18. The monolithic acoustic valve of  claim 14 , wherein the perforated insulated silicon backplate comprises an insulated anti-sticking bump ring and/or a plurality of insulated anti-sticking bumps. 
     
     
       19. The monolithic acoustic valve of  claim 14 , wherein the substrate comprises a cantilevered silicon substrate.